I got an 8 GB Zune with 128 kbps mp3 songs on it, but i only have 1 mb left on my Zune. I have all the songs on my computer, but I want to reduce the size to add more songs. I have expensive head phones, so what would y'all recommend i put the quality to.

Are the files on your computer lossless or 128kbps MP3?

If they're lossless, I'd recommend trying a couple of VBR settings using LAME; -V5 and -V6. Listen and compare songs of each quality (preferably conducting an ABX test) to determine which is transparent to you.

However, if you only have the 128kbps MP3s, the only desirable option is to use MP3packer to reduce the size (by converting them to VBR) losslessly.

Note that when I say "compare songs of each quality", I mean compare each (-V5 and -V6) separately against the original audio/lossless rip. ie. Test/ABX "-V5 vs original" and "-V6 vs original" for each song you choose.

Edit: You could also have a look at AAC as it is quite good at low bitrates. Nero AAC is generally the most preferred AAC encoder.